1. Field of the Invention
The present invention relates to a wiring pattern of a bridge circuit including a magnetic detecting element which is installed in, in particular, a current sensor.
2. Description of the Related Art
FIG. 6 is a planar structure of a current sensor according to a comparative embodiment for comparison with the present invention.
Reference numeral 100 indicates a feedback coil. Only an inner edge and an outer edge of the feedback coil 100 are illustrated. A plurality of resistance elements 101 to 104 is installed under the feedback coil 100. In FIG. 6, each of the resistance elements 101 to 104 is drawn as a see-through part.
The feedback coil 100 is wound in a spiral shape, and a spatial portion 100a is provided at the inner edge side. The feedback coil 100 is provided with a first magnetic field generating portion 100b which is positioned at a Y1 side, and a second magnetic field generating portion 100c which is positioned at a Y2 side. Below the first magnetic field generating portion 100b, two resistance elements 101 and 104 are disposed via an insulating layer (not illustrated) interposed therebetween. In addition, below the second magnetic field generating portion 100c, two resistance elements 102 and 103 are disposed via an insulating layer (not illustrated) interposed therebetween.
As shown in FIG. 6, a bridge circuit is formed by the four resistance elements 101 to 104. A wiring pattern connected to input terminal 105, ground terminals 106 and 107 and output terminals 108 and 109, and a wiring pattern connected between each element, are routed as shown in FIG. 6.
In the wiring patterns, wiring patterns 110 and 111 for connecting between the resistance elements 101 and 102 (103 and 104), which are connected in series to each other, intersect with each other via an insulating layer (not illustrated) therebetween at the position of the spatial portion 100a of the feedback coil 100.
However, since the insulating layer interposed between the wiring patterns 110 and 111 is formed not to have too large a thickness so as to magnetically couple the feedback coil 100 and the resistance elements 101 to 104, there is a concern about the insulation properties between the intersected wiring patterns 110 and 111. In addition, since the wiring patterns 110 and 111 should be formed at another level while the insulating layer is interposed therebetween, there is a problem that a manufacturing process becomes longer. Further, a parasitic capacitance is also generated between the intersected wiring patterns 110 and 111. Accordingly, there is a problem that a stable electric characteristics are not obtained.
In the invention disclosed in PCT Japanese Translation Patent Publication No. 2005-515667, wiring patterns constituting a bridge circuit do not interset with each other, but an inner region between resistance elements configuring the bridge circuit is not used as a routing region of the wiring pattern. For this reason, it is difficult to effectively route the wiring patterns in a narrow region. Moreover, the invention disclosed in PCT Japanese Translation Patent Publication No. 2005-515667 is not intended for use with a spin valve element.
PCT Japanese Translation Patent Publication No. 2003-526083, Japanese Unexamined Patent Application Publication No. 60-69906, and Patent Document 4: Japanese Unexamined Patent Application Publication No. 64-32712 are examples of related art.